The present invention relates to a system for the timely flushing and recovery of residues from a pouring chute on a cement truck in order to prevent them from hardening in the chute and more particularly to a self-contained system that is transportable with the truck.
Cement and concrete mixes are frequently delivered by a so-called xe2x80x9ctransit mixerxe2x80x9d. The transit mixer is a truck with a rotatable mixing drum, into which batch ingredients are loaded. The raw materials are mixed by rotating the drum as the truck proceeds to its intended destination, where the cement is poured as required. This procedure is well known in prior art.
A major issue in the construction industries is how best to clean and recycle residual materials out of the system. Residues, if not removed from the truck soon enough, harden and present the operator with an enormous cleaning problem. Also it is to the operator""s advantage to handle residues in an environmentally benign manner, since this avoids both legal sanctions and the wastage of materials which have an economic value. The issues of removing and recycling residual material are the subject of prior art, as exemplified by U.S. Pat. Nos. 3,596,759, 3,886,063, 3,997,434, 4,016,978, 4,127,478, 4,285,808 and 5,127,740. Washing and material reclamation systems are described in U.S. Pat. No. 3,997,434 and 4,285,808; however, these deal with systems wherein the residues are washed directly out of the transit mixer into stationary handling equipment located at some base of operations. U.S. Pat. No. 5,127,740 describes a system wherein a chemical retardant is added to excess mixture to delay its hardening, and a chemical accelerant is subsequently added to restore the original hardening characteristics of the mixture when it is once again needed for use. U.S. Pat. No. 4,016,978 describes a mobile cleaning and separating system which is appended to the truck, and is intended to deal with excess material remaining in the mixing drum.
Normally the mixing drum is cleaned out after returning to its base, but the pouring chute, which directs the transfer of material from the mixing drum to its intended point of discharge, must be cleaned immediately after each use. The residue in the pouring nozzle has a high surface area relative to its volume, and therefore dries very rapidly. This inevitably accelerates its hardening. Currently available alternatives include flushing out the nozzle with water and allowing the products of flushing to be dumped at the site, which is environmentally undesirable, or collecting them in an improvised container.
It is the primary purpose of the present invention to provide a convenient portable system to allow the operator to flush out the pouring nozzle with water so that the washed out solids are retained in a strainer and the resulting slurry is directed into the mixer drum. The system is affixed to the truck and constructed so that the strainer can be retracted and stowed close against the truck when not in its operative position. When the truck returns to its depot, the drum is cleaned in the normal way at a cleaning station. and the contents of the strainer are merged with like residues from other sources to be recycled.